Embodiments of the invention relate to an electronic component with a semiconductor substrate for a micro-electromechanical system, an active top side on the semiconductor substrate having an active surface area which is covered by a self-supporting electrically conductive covering element. Furthermore, embodiments of the invention relate to a semiconductor wafer having a number of such components and to a method for producing such an electronic component or semiconductor wafer, respectively.
Furthermore, embodiments of the present invention concern radio frequency (RF) filters and pertains particularly to mounting film bulk acoustic wave filters (BAW filters) in microwave packages using “wafer-level-package” technology. BAW filter die are placed within hermetically sealed packages which are known e.g. from the U.S. Pat. No. 5,872,493, incorporated herein by reference.
BAW filters can be fabricated to include various known types of BAW resonators. These known types of BAW resonators comprise three basic portions. A first one of the portions, which is used to generate acoustic waves, includes an acoustically-active piezoelectric layer. This layer may comprise, by example, zinc-oxide (ZnO), aluminum nitride (AlN), zinc-sulfur (ZnS), or any other suitable piezoelectric material that can be fabricated as a thin film. A second one of the portions includes electrodes that are formed on opposite sides of the piezoelectric layer. A third portion of the BAW resonator includes a mechanism for acoustically isolating the substrate from vibrations produced by the piezoelectric layer. BAW resonators are typically fabricated on silicon, gallium arsenide, or glass substrates using thin film technology (e.g., sputtering, chemical vapor deposition, etc.). BAW resonators exhibit series and parallel resonances that are similar to those of, by example, crystal resonators. Resonant frequencies of BAW resonators can typically range from about 0.5 GH to 5 GHz, depending on the layer thicknesses of the devices.
For applications such as cellular phones, it is desirable to reduce the size of components. Particularly, it is desirable to integrate RF duplexers and filters as part of a radio-on-a-die with a manufacturable technology.